Knitted textile materials comprising polyester fibers and having outstanding soil release and durable press properties and a process for the preparation thereof

ABSTRACT

POLYESTER KNITTED TEXTILE MATERIALS, SUCH AS FABRICS, HAVING OUTSTANDING SOIL RELEASE AND DURABLE PRESS PROPERTIES ARE PREPARED BY TREATING THE KNITTED MATERIAL COMPRISING POLYESTER FIBERS WITH A SUFFICIENT AMOUNT OF A WATER-INSOLUBLE LINEAR ADDITION POLYMER OF ONE OR MORE MONOETHYLENICALLY UNSATURATED MONOMERIC COMPOUNDS AND CONTAINING UP TO ABOUT 5 PERCENT BY WEIGHT OF ACID, PRESENT AS ACRYLIC ACID, METHACRYLIC ACID, AND/OR ITACONIC ACID, IN CONJUNCTION WITH A TEXTILE RESIN AND A TEXTILE RESIN CATALYST FOLLOWED BY THE CURING OF THE TEXTILE RESIN TO FIX THE ADDITIVES TO THE KNITTED FABRIC. THE SO-TREATED TEXTILE MATERIAL OR FABRIC MAY THEN BE PROCESSED BY CONVENTIONAL METHODS TO GARMENTS AND OTHER TEXTILE MATERIALS FOR VARIOUS USES HAVING OUTSTANDING SOIL RELEASE AND DURABLE PRESS PROPERTIES.

United States Patent 3,702,231 KNITTED TEXTILE MATERIALS COMPRISING POLYESTER FIBERS AND HAVING OUT- STANDING SOIL RELEASE AND DURABLE PRESS PROPERTIES AND A PROCESS FOR THE PREPARATION THEREOF Edwin L. Dale, Spartanburg, S.C., assignor to Beaunit Corporation, New York, N.Y. No Drawing. Filed Sept. 16, 1968, Ser. No. 762,311 Int. Cl. D06m 1.5/36, 15/38, 15/58 U.S. Cl. 8115.6 4 Claims ABSTRACT OF THE DISCLOSURE Polyester knitted textile materials, such as fabrics, having outstanding soil release and durable press properties are prepared by treating the knitted material comprising polyester fibers with a sufficient amount of a water-insoluble linear addition polymer of one or more monoethylenically unsaturated monomeric compounds and containing up to about percent by weight of acid, present as acrylic acid, methacrylic acid, and/or itaconic acid, in conjunction with a textile resin and a textile resin catalyst followed by the curing of the textile resin to fix the additives to the knitted fabric. The so-treated textile material or fabric may then be processed by conventional methods to garments and other textile materials for various uses having outstanding soil release and durable press properties.

BACKGROUND OF THE INVENTION (1) Field of the invention This invention relates to knitted materials comprising polyester fibers and having outstanding soil release and durable press properties and to a process for the preparation thereof.

(2) Description of the prior art Polyester blends have become widely used in the preparation of many types of garments, particularly in connection with durable press garments. Durable press properties are generally achieved by the application of a textile resin and textile resin catalyst to the fabric or garment followed by a curing of the resin on the fabric or garment. This procedure has led to improved durable press properties with a corresponding deterioration of the soil release characteristics of the fabric or garment. For this reason, if a durable press garment becomes soiled, it is very difiicult and nearly impossible to remove soil and/or oily stains from the garment. Where some of the undesirable soil and dirt is removed during a washing cycle, the soil and dirt in the wash water is redeposited onto the garment prior to the completion of the laundering. Consequently, after laundering, the garment will retain a substantial amount of the soil or dirt. After a number of such washings, the intensity of the discoloration will reach a point where the garment will be unacceptable for further wear.

A substantial amount of research has been carried out toward solving the problems discussed above and a number of patents have issued in this area. U.S. Pats. 3,125,- 405 to Gordon; 3,125,406 to Herman; and 3,246,946 to Gordon are directed to the production of permanent press garments composed predominantly of cellulosic fibers or yarns but do not disclose or suggest means for obtaining release of soil from the treated garments. U.S. Pat. 3,377,- 249 to Marco is directed to the production of a durable press garment which also has a high degree of soil release by applying to the fabric or garment a textile resin, a textile resin catalyst and a synthetic acid emulsion polymer followed by the curing of the textile resin. The

Patented Nov. 7, 1972 SUMMARY OF THE INVENTION It is the object of the present invention to provide knitted textile materials, such as fabrics, comprised of polyester fibers and having outstanding soil release and durable press properties after repeated washings.

The object of the present invention is accomplished by applying to the knitted polyester material'a textile resin, a textile resin catalyst and a water-insoluble linear addition polymer of one or more monoethylenically unsaturated monomeric compounds and containing up to about 5 percent by weight of acid, present as acrylic acid, methacrylic acid and/ or itaconic acid and curing the textile resin to fix or bond the additives to the knitted material, said water-insoluble linear addition polymer being added in an amount suificient to provide durable soil release properties to the treated knitted material.

The treated knitted materials of this invention may be further processed by conventional means to provide a number of textile materials for various end uses. The treated knitted fabrics of this invention are particularly applicable to processing by conventional means into knitted garments for use in an increasingly important knit wear market.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The materials to be treated according to the present invention are preferably knitted fabrics comprised of at least 50 percent by weight of polyester fibers. The knitted fabrics may consist wholly of polyester fibers or they may consist of blends of polyester fibers with other fibers, such as cotton, rayon, acrylics, and the like. It is preferred that the knitted fabrics treated in accordance with the present invention be blends of polyester fibers with cellulosic fibers wherein the polyester fibers comprise from about 50 to percent of the total weight of the blend with about 25 to 50 percent of the blend being composed of the cellulosic fibers, such as cotton. The polyester fibers which make up at least 50 percent by weight of the knitted fabric may be any of the conventional, linear, fiber-forming polyesters which are well known to those skilled in the art. Preferably, the polyester fibers used for the purposes of the present invention are prepared from polyethylene terephthalate.

U.S. Pat. 3,377,249 to Marco teaches the production of a durable press fabric which also has a high degree of soil release by applying to the fabric a textile resin, a textile resin catalyst and a synthetic acid emulsion polymer followed by the curing of the textile resin. However, this patent teaches that it is critical that the acid emulsion polymer contain at least 20 percent by weight of acid, calculated as acrylic acid, in order to provide adequate soil release properties to the treated fabric. It has been found that this is true when treating woven and nonwoven fabrics. However, surprisingly, it has been found that in the treatment of knitted fabrics the emulsion polymers of low acid content, up to about 5 percent by weight, as defined herein, although not particularly effective in providing acceptable soil release properties in regard to woven and nonwoven fabrics provide excellent soil release properties in conjunction with durable press properties. For this reason, it is critical to the present invention that the treated material for the purposes of the present invention be a knitted fabric rather than a woven or nonwoven fabric. It has also been found that the use of acid emulsion polymers containing high acid content does not appear to provide adequate soil release properties for knitted fabrics and in addition, does not enhance other properties, such as strength, as does the use of low acid content polymers.

The problem of soil release is particularly troublesome when the knitted fabric contains predominantly polyester fibers. The polyester fibers are hydrophobic and therefore repel the water necessary for cleaning the fabric in addition to attracting the soil particles. It has also been found that the treatment of the fabric with textile resins and textile resin catalysts to provide durable press properties to the fabric adversely affects the soil release properties present in the fabric. Therefore, the treatment of knitted fabrics containing at least 50 percent by weight of polyester fiber to provide both durable press and soil release properties is highly desirable.

The present invention involves the treatment of knitted textile materials, such as fabrics, comprising polyester fibers with a textile resin, a textile resin catalyst and a water-insoluble linear addition polymer of low acid content to impart to the fabric so treated both durable press and soil release properties. The textile resin, the textile resin catalyst and the water-insoluble linear addition polymer may be applied to the knitted fabric by any convenient means. It is necessary only that the additives provide a coating or film upon or around the fabric being treated. A convenient method of treating the knitted fabrics in accordance with the present invention is to simply pad the additive onto the fabric from a bath which contains the additives in amounts suflicient to provide effective amounts of each additive upon the fabric surface. The treated fabric may be dried and then is subjected to a conventional curing treatment whereby the textile resin is cross-linked with and/ or thermoset on the knitted fabric.

The textile resin and the water-insoluble linear addition polymer may be applied to the fabric from the same or separate bath treatment followed by curing with little or no effect upon the soil release properties of the treated knitted fabric. However, when the textile resin is applied to the fabric and cured thereon prior to treating the fabric with the water-insoluble linear addition polymer, the initial soil release is improved but the durability of the soil release properties is decreased. Therefore, it is normally preferable to treat the fabric simultaneously with the two additives or separately where the water-insoluble linear addition polymer is added first followed by the textile resin.

It should also be pointed out that other ingredients may be placed in the treating bath besides the additives of this invention in order to improve other characteristics of the treated fabrics. Illustrative of other agents which may be conveniently employed in the treating bath are antistatic agents, softeners, dyestuffs, lubricants, wetting agents, emulsifying agents, dispersing agents, and the like.

Generally, the application of the treating bath is controlled to provide from about 30 to 100 percent by weight wet pickup by the fabric from the treating bath. Preferably, a wet pickup of from about 50 to 75 percent by Weight from the bath is desired.

The polymers used in accordance with this invention to provide soil release properties to knitted polyester fabrics are water-insoluble linear addition polymers of one or more monoethylenically unsaturated monomeric compounds and of zero or low acid content, containing up to about percent by weight of acid, present as acrylic acid, methacrylic acid, and/or itaconic acid. These polymers are prepared by copolymerizing acrylic acid, methacrylic acid and/or itaconic acid wtih one or more other copolymerizable compounds containing a single vinylidene group, such as esters of acrylic acid or methacrylic acid and monohydric alcohols such as methyl, ethyl, butyl, oc'tyl, dodecyl, cyclohexyl, cyanoethyl, aminoethyl, and the like; esters of itaconic acid and the above alcohols;

esters from maleic, fumaric, or citraconic acids, and the above alcohols; vinyl esters of carboxylic acids such as acetic, propionic, butyric, and the like; vinyloxyalkyl esters such as vinyloxyethyl acetate and the like; vinyl ethers such as ethyl vinyl ether, butyl vinyl ether, octyl vinyl ether, hydroxyethyl vinyl ether, aminoethyl vinyl ether, aminopropyl vinyl ether, dimethylaminoethyl vinyl ether, vinyloxyethoxyethanol, vinyloxypropoxyethanol; methacrylonitrile or acrylonitrile; acrylamide, or methacrylamide, and N-substituted amides of these types; vinyl chloride, vinyl bromide, vinylidene chloride, vinylidene fluoride, l-chloro-l-fiuoroethylene, ethylene, styrene, 2- vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyridine and the like. These water-insoluble polymers may be dispersed by means of conventional non-ionic dispersing agents, if so desired. Salts, such as sodium, potassium, and the like, of the above listed acid polymers may also be used. It is necessary that the polymer used be stable under the conditions of application. For the purposes of the present invention, it is preferred that the soil release polymer used is a polymer derived from an acrylic ester, such as methyl or ethyl acrylate, methyl or ethyl methacrylate, or combinations thereof or a copolymer of acrylic acid or methacrylic acid with an acrylic ester such as methyl or ethyl methacrylate or methyl or ethyl acrylate. The polymer or co-polymer preferably will contain less than about 2 percent by weight of acrylic or methacrylic acid. An ethyl acrylate polymer containing about 1 percent by weight of acrylic acid is most preferred for the purposes of this invention. This polymer forms a milky emulsion in water, is nonionic and has a pH of about 3.0. It is available from Rohm and Haas Company, Philadelphia, Pa., under the trade name Rhoplex HA-l2.

These polymers may be applied in varying amounts to the knitted fabric to provide soil release properties according to this invention. Soil release properties as referred to throughout this disclosure relate to the ability of the treated fabric to be Washed to remove soil and/or oily stains present and to its ability to resist redeposition of the soil onto the fabric from the wash water. As expected, the soil release abilities of a treated fabric will increase as the amount of Soil release polymer used is increased.

It has been found that these soil release polymers may be applied to the knitted fabric as aqueous dispersions containing from about 0.25 to 5 percent by Weight of soil release polymer in the treating bath to provide at least about 0.25 percent by weight of soil release polymer on the knitted fabric, based upon dry weight. Preferably, it has been found that from about 1 to 3 percent by weight of soil release polymer on the knitted fabric, based upon dry weight of the fabric, is desired.

The textile resins used in accordance with the present invention include monomers and polymers which when applied to a knitted polyester containing fabric and then reacted under certain conditions undergo polymerization and/or condensation to a thermoset state. These resins include the aminoplast textile resins which are conventional to those skilled in the art for imparting durable press characteristics to fabrics and the like. These aminoplast resins are nitrogen containing resins which when applied to a textile material such as a fabric or garment, in the presence of a suitable catalyst at temperatures of from about C. to about 200 C. are cured or transformed into the thermoset state. Preferably, curing temperatures of from about to C. are used. The aminoplast resin condenses with any cellulose molecules present in the fabric and, in addition, the resin undergoes polymerization with itself when cured. This procedure essentially bonds the resin to the fabric and provides for the durable press characteristics. Where the soil release polymer is applied to the fabric prior to the curing of the textile resin, the durability of the soil release properties is enhanced due apparently to binding or fixing action of the curing treatment.

As pointed out above, the textile resins which may be used for the purposes of this invention are those conventionally used for imparting durable press characteristics to fabrics. U.S. Pat. 3,377,249 to Marco, at columns and 6, provides a good list of textile resins which may be used for the purposes of this invention and is incorporated herein by reference. It is preferred that the textile resin used be dimethylol ethylene urea or dihydroxy dimethylol ethylene urea.

The amount of textile resin used depends to a great extent upon the end use desired for the treated fabric. For this reason, the amount of textile resin which may be used will vary over a large range. Preferably, the amount of textile resin used will be that sufficient to provide good durable press characteristics and not so much to adversely affect the hand or handle of the fabric. It has been found that the application bath may conveniently contain from about 5 to 25 percent by weight of textile resin and preferably from about to percent by weight. The amount of resin applied to the fabric may range from about 2 to percent by weight of the dry weight of the fabric and preferably will range from 4 to 10 percent.

The textile resin catalysts which are used in conjunction with the textile resins will be selected based upon the particular textile resin employed and are conventional to those skilled in the art. Where the textile resin used has a functional group which is reactive under acidic conditions, then an acid catalyst is used. Where the textile resin used has a functional group which is reactive under alkaline conditions, then a base catalyst is employed. Both types of catalyst are used where acid and alkaline reactive functional groups are present in the textile resin employed. Where acid and base catalysts are added together, they must be selected so that they will not initiate the two reactions at the same time but in some determined sequence.

As pointed out above, the acid and base textile resin catalysts which may be used for the purposes of this invention are those conventionally used for activating the reactions of the textile resins employed herein to provide durable press characteristics to fabrics. U.S. Pat. 3,377,249 to Marco, at columns 6 and 7, provides a good discussion of textile resin catalysts which may be used for the purposes of this invention and is incorporated herein by reference. It is preferred that the textile resin catalyst used be zinc nitrate or magnesium chloride.

The amount of textile resin catalyst used for the purposes of this invention is that amount conventionally used in connection with textile resins to provide durable press characteristics to fabrics. This amount is dependent upon the particular textile resin used, the conditions employed, and the nature of the catalyst used. Generally, the textile resin catalyst is used in the application bath in amounts of up to about 10 percent by weight. It is preferred that the textile catalysts be used in amounts of from about 0.5 to 3 percent.

Durable press and soil release garments made from the knitted fabrics treated according to this invention are processed by conventional steps. The garment may be folded and pressed on conventional equipment, such as a Hoffman press, as is standard in the industry and this treatment generally involves pressing the garment for a short time followed by a curing operation in an oven to obtain any desired configuration. Other conventional treatments known to those skilled in the art may also be used.

Normally, the knitted fabric is treated according to this invention with an application bath containing the textile resin, the soil release polymer and the textile resin catalyst; then the treated fabric may be dried without curing; a garment having any desired presses and creases is prepared from the treated fabric; and the garment is then subjected to textile resin curing conditions to provide a garment made from the treated knitted fabric having outstanding durable press and soil release characteristics. It is also equally convenient to simply treat the fabric followed by the curing step without an intermediate drying step. The fabric may then be conventionally processed to provide the desired end product.

Temperatures which may be used to dry the treated or coated fabric depend upon the particular additives employed. These temperatures should not be in the range which will cause curing or reaction to take place. Generally, these temperatures will range from about to 145 C. and the fabric will be dried at a rate of about 10 to 70 yards per minute. This step is preferably carried out on a tenter frame. Care should be taken in the higher drying temperature ranges so as not to cause initiation of the curing and/or reaction.

When an aminoplast resin having ethylenic unsaturation is applied to the fabric, an irradiation step may be employed using commercially available irradiation equipment and conventional techniques. The amount of ionizing irradiation necessary according to the present invention is about 32 or above electron volts per ion pair formed. High energy particle and ionizing irradiation are both useful for the purposes of the present invention. The dosage of irradiation which may be used is in the range of one thousand rads to one hundred megarads, a rad being the amount of high energy irradiation of the type which results in energy absorption of one hundred ergs per gram of absorbing material.

Curing of the textile resin is accomplished by conventional means where the treated fabric is subjected to conditions such that the catalyst present on the fabric initiates the crosslinking reaction between functional groups of the textile resin and the hydroxyl groups of any cellulose present in the fabric and converts the resin to a thermoset state. When the treated fabric consists of 100 percent of polyester fibers, then the textile resin adheres to or is fixed to the fabric by being converted to a thermoset state. Heating of the fabric normally initiates the curing and this is normally done at about C. to about 200 C. in hot air or steam for a ti mesufiicient to cause reaction of and/or curing of the textile resin, normally about 1 to 15 minutes. Preferably, the curing will be conducted at about 145 to 175 C. for a period of 2 to 10 minutes. Where the textile resin contains two different functional groups, then two curing steps are carried out using different conditions for each cure.

The following examples are presented as a further disclosure and illustration of the improved products of this invention and are not intended as a limitation thereof. All parts, proportions, and percentages are by weight unless otherwise indicated.

The soil release ratings used in the examples are obtained by comparing the residual oil stains in the washed fabric to a set of standards having numerical ratings from 1.0 to 5.0, 1.0 being very poor, and 5.0 representing virtually complete removal of the stains.

The bursting strengths given in the examples are obtained by subjecting the fabric to the Mullen Burst Test as described in ASTM D-231.

EXAMPLE 1 A knitted fabric comprising about 65 percent of polyethylene terephthalate and about 35 percent of cotton having been treated with no finish was stained with an extra heavy mineral oil and subjected to one normal cycle home washing in an automatic washer using one cup of Tide, 8. commercial detergent, and at a water temperature of about to F. The fabric is rinsed at about 100 to 110 F. and then tumbled dry on high setting in a home dryer for about 50 minutes.

The washed fabric had good strength, a good band, a percent shrinkage of '6 percent in length and 2 percent in width and a soil release rating of 1 to 2.

7 EXAMPLE 2 The washed fabric had a good strength, a good hand, a

percent shrinkage of about 6 percent in length and about 2 percent in width and a soil release rating of about 2.

EXAMPLE 3 A knitted fabric comprising about 65 percent of polyethylene terephthalate and about 35 percent of cotton was padded with an aqueous pad bath comprising about 7 percent of dihydroxy dimethylol ethylene urea, about 0.5 percent of zinc nitrate, about 2 percent of an ethyl acrylate polymer containing about 1 percent acid, and about 1 percent of Softex B to provide about 10 percent dry finish pickup. The treated fabric was then cured for about 3 minutes at a temperature of about 145 C. The fabric was stained, washed and dried as described in Example 1.

The washed fabric had good strength, a good hand, a percent shrinkage of about 6 percent in length and percent in width and a soil release rating of about 4 to 5.

EXAMPLE 4 A knitted fabric comprising about 65 percent of polyethylene terephthalate and about 35 percent of cotton was padded with an aqueous pad bath comprising about 7 percent of dihydroxy dimethylol ethylene urea, about 0.5 percent of zinc nitrate and about 2 percent of an ethyl acrylate polymer containing about 1 percent acid to provide about 10 percent dry finish pickup. The treated fabric was then cured for about 3 minutes at a temperature of about 145 C. The fabric was stained, washed and dried as described in Example 1.

The washed fabric had good strength, a slightly harsh hand, a percent shrinkage of about 6 percent in length and about 2 percent in width and a soil release rating of about 4 to 5.

EXAMPLE 5 A knitted fabric comprising about 50 percent of polyethylene terephthalate and about 50 percent of cotton was padded with an aqueous pad bath of the composition described in Example 4. The treated fabric was then cured for about 3 minutes at a temperature of about 145 C. The fabric was stained, washed and dried as described in Example 1. Complete washout of the stain was observed.

EXAMPLE 6 A knitted fabric comprising about 50 percent of polyethylene terephthalate and about 50 percent of cotton was padded with an aqueous pad bath comprising about percent of dihydroxy dimethylol ethylene urea, about 0.85 percent of zinc nitrate, about 1 percent of Softex B, and about 2 percent of an ethyl acrylate polymer containing less than about 0.1 percent of acid to provide about 75 percent wet pickup. The treated fabric was then cured for 10 minutes at a temperature of about 175 C. The fabric was stained with mineral oil, Wesson oil, 3 in 1 oil, and mustard, Washed and dried as described in Example 1. The fabric was washed four additional times, then restained and washed again.

The treated fabric had the following properties: a bursting strength of about 64.4 and a percent shrinkage of about 6.3 percent in length and about .5 percent in width after the first wash and about 7 percent in length and about 1 percent in width after the sixth wash.

The following soil release ratings were made:

A knitted fabric comprising about 50 percent of polyethylene terephthalate and about 50 percent of cotton was padded with an aqueous pad bath comprising about 10 percent of dihydroxy dimethylol ethylene urea, about 0.85 percent of zinc nitrate, about 1 percent of Softex B, and about 2 percent of an ethyl acrylate polymer containing about 9 percent of acid to provide about percent wet pickup. The treated fabric was then cured for 10 minutes at a temperature of about 175 C. The fabric was stained with mineral oil, Wesson oil, 3 in 1 oil and mustard, Washed and dried as described in Example 1. The fabric was washed four additional times, then restained and washed again.

The treated fabric had the following properties: a bursting strength of about 56.2 and a percent shrinkage of about 2.2 percent in length and about 1.5 percent in width after the first Wash and about 2.7 percent in length and.

about 1.5 percent in width after the sixth wash.

The following soil release ratings for the treated fabric were made:

It is understood that changes and variations may be made in the present invention by one skilled in the art without departing from the spirit and scope thereof as defined in the appended claims.

What is claimed is:

1. A process for imparting soil release and durable press characteristics to a knitted fabric comprising about 50 to 75 percent by weight of linear polyester fibers and about 25 to 50 percent by weight of cellulosic fibers which comprises applying thereto an aqueous dispersion comprising about 5 to 25 percent by weight of a textile resin, up to about 10 percent by weight of a textile resin catalyst and about 0.25 to 5 percent by weight of a water-insoluble polymer containing up to about 1 percent by Weight of acid prepared by copolymerizing at least one monoethylenically unsaturated acid with an ester of a monoethylenically unsaturated acid having no free carboxyl groups and thereafter heating the knitted fabric at a temperature of about to 200 C. for a time sufiicient to cure the textile resin.

2. A process as defined in claim 1 wherein the textile resin is dihydroxy dimethylol ethylene urea, the textile resin catalyst is zinc nitrate and the Water-insoluble polymer is an ethyl acrylate polymer containing about 1 percent by weight of acrylic acid.

3. A knitted fabric prepared in accordance with the process described in claim 1.

4. A knitted fabric prepared in accordance with the process described in claim 2.

(References on following page) 10 References Cited 3,401,006 9/1968 Perrino 8115.6

UNITED STATES PATENTS 3, 77,249 4/19 8 Marco 8115.6 3; 22 g GEORGE F. LESMES, Primary Examiner 11/1970 M arc Z IIiiLLZtI: 8:1156 5 CANNON, Assistant Examiner 3/1964 Schlack et a1. 8----116.3

7/1970 Swidler 8-115.6

3/1964 Herman 8-1163 8115.7, 116.2, 116.3, Dig. 4, Dig. 18; 38-144; 117 12/1950 Seymour -8-62 10 93.31, 138.8 A, 138.8 F, 139.4, 143 A, 161 LN, 161 UZ, 10/1969 Bolinger 8127.5 161 UN, 161=UC, 161 UB; 2 243 12/1965 Wilfert 260 29.4 

